Hopes high for Nantucket Ice Bear

NANTUCKET — The Nantucket Board of Selectmen approved a lease agreement Wednesday that could pave the way for free or reduced-cost thermal energy storage at homes on the island.

The lease with Genbright, a Massachusetts-based project developer, allows for the installation of a thermal storage and air-conditioning unit known as an Ice Bear at the town’s Building and Planning Department, at no cost to the town. Genbright has touted the unit, made by a company called Ice Energy, as a way to improve efficiency and bring down the island’s peak energy demand in the summer months.

Nantucket gets all of its electricity from two undersea cables that run from the mainland to the island. It is projected that a third cable will be needed eventually and could cost more than $100 million.

The Genbright project is one of several on Nantucket that are aimed to stave off the large electric infrastructure investments like another cable and rein in the town’s peak electric use, which is growing at five times the state average.

“Nantucket has a surging peak demand that could bring on a third undersea cable at a significant cost to taxpayers," said Lauren Sinatra, the town energy coordinator.

Last summer, Genbright won a $1.5 million grant from the state to put in Ice Energy thermal energy storage air-conditioning units at homes on Nantucket. But some residents were unsure if the Ice Bear units would work for their homes, prompting the town be the first to use them as a kind of show-and-tell, Sinatra said.

Because the town would be benefiting, there was lots of legal red tape to go through, she said, and the project needed the blessing of the selectmen.

The unit will be installed at the town building at 2 Fairgrounds Road and will be leased to the town for three years with a possibility for an extension.

During off-peak hours, the unit stores cooling energy by freezing water in an insulated tank, while still allowing heat or air-conditioning, said Joe Crespo, the chief executive officer of Genbright. During peak air-conditioning hours the Ice Bear melts the ice to provide cooling to the building it's attached to while reducing the load on the power grid.

Genbright proposes to provided 20 units to homeowners at no cost, and 195 will be available at a reduced price.

The units should reduce about 1 megawatt of power off the peak load, Crespo said, and documents from Ice Energy note that four hours of ice cooling would reduce power usage by 95 percent without compromising a homeowner’s comfort.

About 80 percent of the peak load can be attributed to residential homes, according to the presentation from Genbright, and air-conditioning dominates summer peak demand on Nantucket at hours slightly later than the rest of the state, between 5 p.m. and 9 p.m.

This is what makes the Ice Bears such a good fit, Crespo said, because they will bring down those skyrocketing energy peaks from the few months a year that air-conditioning is used.

When the grant was announced in the summer, state Sen. Julian Cyr, D-Truro, and state Rep. Dylan Fernandes, D-Falmouth, praised the project.

“As Nantucket struggles with how to meet its energy needs, it is crucial that we continue to deliver innovative solutions that lower costs for island residents,” Fernandes was quoted in a statement. “Genbright's $1.5 million grant to harness thermal energy storage on Nantucket is an important step towards lessening the impacts of peak demand usage on the island.”

— Follow Ethan Genter on Twitter: @EthanGenterCCT.

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